854
Journal of Paleontology 92(5):850–871
variability can be understood. This is especially true for the arms that are extremely high for a crinoid with such a small aboral cup. Also, the unusual morphology of the column can be described. As noted in the description, the column is cryptically pentameric, and aligned with the pentamere sutures is a series of circular structures filled with a dark matrix. One broken portion of the column reveals that this structure is an unbranched canal penetrating from the outside into the column. To fully detail the morphology of these canals, columns would need to be sectioned. However, because of the scarcity of specimens of Eustenocrinus springeri, this was not done. In the traditional (Ulrich, 1925) interpretation, Eustenocrinus
Figure 3. Eustenocrinus springeri Ulrich, 1925, USNM S 2148, camera lucida drawings: (1, 2) Cross-sectional shapes of ‘appendages’;(1)cross sectionofaplate from the dominant column of anal sac plates; (2) cross section of brachial on E-ray arm; (3, 4) plate diagrams; (3) AB interray lateral view, compare to Figure 1.1; (4) CD interray lateral view, compare to Figure 1.2. Black filling, superradial plates; horizontal ruling, infraradial plates; gray shading, matrix. Scale bar=1.0mm.
First primibrachial completely or partially fixed; nonaxillary primibrachials and more proximal secundibrachials approximately as wide as high, gently convex; more distal brachials can be higher than wide. Ramules typically branching from every third secundi- brachial; ramules branching endotomously (as presently known). Ramules very long and narrow; ramulars higher than wide. Column >40mm long, circular, heteromorphic (Fig. 2.5),
cryptically pentameric. Series of circular, dark calcite structures (infilling of pores) along cryptic pentamere sutures more or less at position of secundinternodals; pore openings of canals penetrating into column. Heights of nodals and internodals irregular; N212 most common columnal arrangement. Lumen pentagonal; details of columnal facets unknown.
Materials.—UMMP 74652−74654; USNM S 2148.
Measurements.—USMN S 2148: ACH, 2.7; ACW, 2.7; AH, 10.6*; CoH, 18.0*. UMMP 74652: ACH, 3.0; ACW, 2.33; AH, 33.0*; CoH, 36.0*.UMMP 74653: ACH, 3.0*; ACW, 1.5; AH, 10.6*; CoH, 18.0*.
Remarks.—With this new material from the Brechin Lager- stätte, this important Ordovician taxon can be more completely characterized, and at least some aspects of its intraspecific
Occurrence.—Ordovician (Katian), Ontario, Canada.
Remarks.—In 1925, Ulrich named Daedalocrinus with his new species D. kirki as the type species. He also reassigned Heterocrinus bellevillensis as a species in Daedalocrinus. Ulrich (1925) distinguished these two species on the basis of size and robustness of the arms. Daedalocrinus bellevillensis had a large crown and robust arms and ramules, whereas D. kirki
has five compound radial plates, four free arms, and the anal series sutured directly above the C superradial. This represents a unique crinoid morphology, and alternative hypotheses discussed but rejected, herein, include: (1) Eustenocrinus has five arms with a small or absent anal sac; and (2) Eustenocrinus has simple radial plates. The appendage in the C ray is comprised of wider plates than brachials in the arms of other rays, and the cross-sectional shape of these ossicles differs fromthose of brachials. The groove on the C ray appendage is broader ‘orally’ and narrower and deeper ‘aborally’ than on the brachials of arms (Fig. 3.1, 3.2). Also note that the proximal C-ray plating is interlocked with adjacent rays (Figs. 2.5, 3.4) compared to the plating between rays with arms (Figs. 2.1, 3.3). Thus, it is reasonable to assume that this is a column of plates that supports an anal sac, as originally suggested by Ulrich (1925). This feature is also unusual because the proximal anal sac is flushwith and enclosed laterallywith adjacent arms before being encased distally within the arms (Fig. 2.2). Eustenocrinus has been traditionally interpreted as having
compound radial plates in all five rays, which is now recognized as a diagnostic character for the Eustenocrinidae. In Eusteno- crinus, the delineation between the radial circlet and the brachials is not clear. However, in Figure 2.1, the sutures between the inferradials and superradials are well sutured, whereas, the superradial-first primibrachial sutures (as well as many brachial-brachial sutures) are somewhat askew. The
material now available is more consistent with this taxon having five compound radial plates rather than five simple radial plates.
Order Homocrinida Ausich, 1998 Family Homocrinidae Kirk, 1914 Genus Daedalocrinus Ulrich, 1925
Type species.—Daedalocrinus kirki Ulrich, 1925, by mono- typy. However, D. kirki is now regarded as a subjective junior synonym of Heterocrinus bellevillensis Billings, 1883 (see Warn and Strimple, 1977).
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